Survey of pediatric MDCT radiation dose from university hospitals in Thailand: a preliminary for national dose survey

Background Increasing pediatric CT usage worldwide needs the optimization of CT protocol examination. Although there are previous published dose reference level (DRL) values, the local DRLs should be established to guide for clinical practice and monitor the CT radiation. Purpose To determine the multidetector CT (MDCT) radiation dose in children in three university hospitals in Thailand in four age groups using the CT dose index (CTDI) and dose length product (DLP). Material and Methods A retrospective review of CT dosimetry in pediatric patients (<15 years of age) who had undergone head, chest, and abdominal MDCT in three major university hospitals in Thailand was performed. Volume CTDI (CTDI(vol)) and DLP were recorded, categorized into four age groups: <1 year, 1-< 5 years, 5-<10 years, and 10-<15 years in each scanner. Range, mean, and third quartile values were compared with the national reference dose levels for CT in pediatric patients from the UK and Switzerland according to International Commission on Radiological Protection (ICRP) recommendation. Results Per age group, the third quartile values for brain, chest, and abdominal CTs were, respectively, in terms of CTDI(vol): 25, 30, 40, and 45 mGy; 4.5, 5.7, 10, and 15.6 mGy; 8.5, 9, 14, and 17 mGy; and in terms of DLP: 400, 570, 610, and 800 mGy cm; 80, 140, 305, and 470 mGy cm; and 190, 275, 560,765 mGy cm. Conclusion This preliminary national dose survey for pediatric CT in Thailand found that the majority of CTDI(vol) and DLP values in brain, chest, and abdominal CTs were still below the diagnostic reference levels (DRLs) from the UK and Switzerland regarding to ICRP recommendation.     

Growing the Mandible: Role of the Periosteum and its Cells

Mandibular periosteum moves in the direction of new apposition. This displacement, usually termed “migration,” is thought to involve the fibrous layer of periosteum, with the deeper osteogenic layer remaining at its original location except for its blood vessels. To assess whether periosteal displacement includes cells as well as matrix and whether the osteogenic layer has a role, a longitudinal study was undertaken. Young pigs (n = 10) were injected with a replication marker and killed 3 hr, 2 weeks, or 4 weeks later. Sections of the mandibular ramus were scored for labeled cell density. Some sections were double‐labeled with lectin to identify blood vessels. Statistical differences were seen between but not within age groups. Three hours after labeling, the fibroblastic layer had sparse, evenly distributed replicating cells, whereas the osteogenic layer had numerous replicating cells, especially at the caudal border. At 2 and 4 weeks later, a decrease in labeled osteogenic layer cells was accompanied by an increase in labeled osteocytes. Zones of labeled osteocytes in these late‐sacrifice groups were used to approximate the position of the ramal borders at the time of injection. Beyond these zones, in active growing sites, labeled cells were found not only in the fibrous layer but also in the osteogenic layer and in bone. Therefore, periosteal displacement does involve cells and is not restricted to the fibrous layer. Anat Rec 290:1366‐1376, 2007. © 2007 Wiley‐Liss, Inc.     

Pediatric renovascular hypertension in Thailand: CT angiographic findings

Background  

Renovascular disease is an uncommon but important cause of hypertension in children. When unrecognized and untreated, renovascular hypertension in children can have serious complications.     

Imaging features of unusual adrenal masses

The widespread use of cross-sectional imaging techniques has resulted in increased detection of adrenal masses. The imaging characteristics of common adrenal masses such as adenoma, phaeochromocytoma and metastasis are well established. In this pictorial essay, the imaging features of unusual adrenal masses including cyst, lymphoma, adrenal carcinoma, myelolipoma, haemangioma, smooth muscle tumour, haematoma, and infection (acute tuberculous adrenitis and histoplasmosis) are presented. Computed tomography permits a diagnosis of cyst, acute or subacute haematoma and myelolipoma. Although the imaging features of other lesions are non-specific, imaging has an important role in the detection of these unusual adrenal masses, and in aiding their diagnosis and management.     

Transitioning from cerebrospinal fluid to blood tests to facilitate diagnosis and disease monitoring in Alzheimer's disease

Alzheimer’s disease (AD) is increasingly prevalent worldwide, and disease-modifying treatments may soon be at hand; hence, now, more than ever, there is a need to develop techniques that allow earlier and more secure diagnosis. Current biomarker-based guidelines for AD diagnosis, which have replaced the historical symptom-based guidelines, rely heavily on neuroimaging and cerebrospinal fluid (CSF) sampling. While these have greatly improved the diagnostic accuracy of AD pathophysiology, they are less practical for application in primary care, population-based and epidemiological settings, or where resources are limited. In contrast, blood is a more accessible and cost-effective source of biomarkers in AD. In this review paper, using the recently proposed amyloid, tau and neurodegeneration [AT(N)] criteria as a framework towards a biological definition of AD, we discuss recent advances in biofluid-based biomarkers, with a particular emphasis on those with potential to be translated into blood-based biomarkers. We provide an overview of the research conducted both in CSF and in blood to draw conclusions on biomarkers that show promise. Given the evidence collated in this review, plasma neurofilament light chain (N) and phosphorylated tau (p-tau; T) show particular potential for translation into clinical practice. However, p-tau requires more comparisons to be conducted between its various epitopes before conclusions can be made as to which one most robustly differentiates AD from non-AD dementias. Plasma amyloid beta (A) would prove invaluable as an early screening modality, but it requires very precise tests and robust pre-analytical protocols.     

Chorioamnionitis is associated with placental transmission of human immunodeficiency virus-1 subtype E in the early gestational period.

The frequency and the cellular basis for HIV-1 transmission from mother to child in the early gestational period are poorly understood. We compared the placentas of 24 women seropositive for HIV-1 subtype E and who had not received any antiretroviral drugs, to placentas of 25 seronegative women. All placentas were obtained during therapeutic abortion at 6-23 weeks gestation. Placentas and fetal organs were examined by routine light microscopy, immunostaining for p24 capsid protein, and in situ PCR to localize which cells were infected with HIV-1 subtype E. The number of previous abortions was not a factor in placental HIV infection since this number was higher in seronegative women (P < 0.01). There were no significant differences between the placentas of the two groups with respect to presence of chorioamnionitis, villitis, villous stromal fibrosis, infarction, abnormal villous maturation, deciduitis or decidual necrosis. HIV-1 subtype E was detected in up to 83% of placentas, either by immunostaining or in situ PCR, in trophoblast, villous stromal cells, Hofbauer cells, decidual and decidual glandular epithelium. Fetal organs were positive for HIV in 30% (6/20) of cases. There was a significant association between transmission of HIV to the fetus and the histologic findings of chorioamnionitis, plasmacellular deciduitis and decidual cell necrosis. This is the first report showing an association of chorioamnionitis with early in utero transmission of HIV-1 subtype E. This may help explain the cases of in utero transmission that persist despite antiretroviral prophylaxis, given that therapy is started in the late gestational period.